BACKGROUND AND PURPOSE:

• Bacterial vaginosis (BV) is common with a high risk for recurrence
• Lactin-V
  • Treatment containing live L. crispatus, a naturally occurring vaginal strain of bacteria
  • Used following metronidazole to encourage vaginal colonization with L. crispatus
• Cohen et al. (NEJM, 2020) conducted a phase 2b trial to assess whether treatment with Lactin-V after metronidazole would result in a significantly lower incidence of recurrence of BV

METHODS:

• Randomized, double-blind, placebo-controlled, phase 2b trial (RCT) 
• Participants
  • Women 18 to 45 years of age with BV
  • Completed course of vaginal metronidazole gel (5-day course)
• Interventions (within 48 hours of completing metronidazole treatment)
  • Vaginally administered Lactin-V for 11 weeks (Lactin-V at 2×109 CFU per dose; carton containing 25 vaginal applicators)
  • Placebo (same inactive ingredients but without live L. crispatus)
• Study design
  • Participants were randomly assigned 2:1 to Lactin-V or placebo
  • Follow up was through week 24
  • Analysis was in intention-to-treat
• Statistical analysis
  • 228 participants required
  • 70% power to detect by week 12 a 50% lower recurrence of BV in the Lactin-V group vs the placebo group
• Primary outcome
  • Percentage of women who had a recurrence of bacterial vaginosis by week 12

RESULTS:

• 228 women were randomized
  • Lactin-V: 152 women
  • Placebo: 76 women
• By week 12 (primary outcome): BV recurrence was significantly lower in the Lactin-V group
  • Lactin-V: 30% (46 participants)
  • Placebo: 45% (34 participants)
  • Risk ratio (RR): 0.66 (95% CI, 0.44 to 0.87; P=0.01)
• By week 24 (secondary outcome):
  • RR: 0.73 (95% CI,  0.54 to 0.92)
• At the 12-week visit, L. crispatus detected in 79% of participants in the Lactin-V group
• Safety
  • No significant difference in the prevalence of adverse events between the two groups, including local vs systemic effects
  • No severe events were associated with treatment or placebo group

CONCLUSION:

• The use of Lactin-V following a 5-day course of metronidazole was associated with a significantly lower incidence of recurrent BV at 12 weeks, compared to placebo with sustained effect through 24 weeks
• Further studies required to determine long-term effectiveness beyond 12 and 24 weeks
• The authors state

These results extend earlier findings seen with Lactin-V and support the general safety of the current formulation and dosing strategy 

Learn More – Primary Sources:

Randomized Trial of Lactin-V to Prevent Recurrence of Bacterial Vaginosis

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